Monthly high-limit setpoint of economizer system in South Korea

An economizer system introduces outdoor air during cooling to reduce cooling loads. It establishes a high-limit threshold to prevent increased energy use of cooling coils when introducing outdoor air at high temperatures. Although the fixed high-limit condition in the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) 90.1 standard Thermal Climate Zone definitions is widely accepted, it is not optimal from the perspective of cooling coil energy consumption. Herein, we propose the most efficient monthly high-limit for cooling coil energy savings in various regions of South Korea using standard climate data from the Korean Solar Energy Society. For this purpose, utilizing the Python GUI tool PyQt5, the standard climate data is inputted to simultaneously analyze the region's climate zone based on CDD10℃ and HDD18℃, the distribution of dry-bulb temperature and enthalpy, and the total annual cooling coil energy based on monthly high- limit. The Thermal Climate Zone analysis aims to determine the appropriate zones according to the ASHRAE recommendations and compare the cooling energy savings achieved by applying the proposed high-limit setpoints. This approach allows for an evaluation of the difference between the ASHRAE fixed high-limit and the newly proposed monthly economizer setpoints. Through this, this study proposed monthly economizer setpoints and cooling energy savings for a total of 64 standard climate datasets across South Korea. The regions analyzed in detail were Jeju, Daegu, Chuncheon, and Daegwallyeong, for which the energy savings achieved by operating the economizer with the monthly setpoints compared to the fixed setpoints were 3.46 %, 5.17 %, 3.56 %, and 7.62 %, respectively.